From ocean shores to grocery stores, plastic is all around us. Scientists are even finding microplastics, which are small bits of plastic under five millimeters long, in over half of human organ systems. That may sound scary, but scientists are still figuring out exactly what their presence means—and if they’re truly harmful for our long-term health.

The good news? “I don't think we can say yet that [microplastics] are everywhere” because it’s such a new area of research, and they’re hard to measure, says Kjersti Aagaard, MD, PhD, the medical director of HCA Healthcare Gulf Coast Division and lead clinician at Texas Maternal Fetal Medicine. Plus, some of the spots where they have been detected—like in human stools and urine—show that microplastics can be cleared from the body, meaning they might not stick around in the long run anyway.

Kjersti Aagaard, MD, PhD, is the medical director of HCA Healthcare Gulf Coast Division and lead clinician at Texas Maternal Fetal Medicine. Stephanie Wright, PhD, is a senior lecturer in environmental toxicology at Imperial College London. Eliseo Castillo, PhD, is an associate professor and director of gastroenterology research at the University of New Mexico.

Ahead, experts explain how microplastics get into our bodies, how they may affect us, and what this all really means for our health.

Microplastics get into your body through food, water, and air, says Stephanie Wright, PhD, a senior lecturer in environmental toxicology at Imperial College London. Given the amount of air humans breathe every day—over 2,000 gallons, per the American Lung Association—inhalation plays a huge role in how microplastics get into the body, she says.

By now, it’s common knowledge that breathing in smoke, dust, mold, and other kinds of particle pollution are generally bad for your health. Since microplastics are tiny, non-natural particles found in the air, Wright says that they can be considered particle pollution, too. Wright says that microplastics are likely not as toxic as lead, mercury, or the carcinogenic chemicals that come from burning oil, gas, or coal; lead poisoning, for example, causes almost one million deaths per year. Still, they’re probably not the best thing to ingest.

A recent 2024 study in the New England Journal of Medicine found that patients with a higher amount of microplastics in their carotid artery plaques were at a higher risk of stroke. Right now, there’s an emerging correlation—but not necessarily a causation—between microplastics and microvascular (heart) disorders, and between microplastics and inflammation, Aagaard says. So, it’s not known whether microplastics are causing the microvascular disorders and inflammation.

Another 2025 study in Nature Medicine found about a spoon’s worth of microplastics in postmortem brains, and found higher concentrations of microplastics in the brains of those with dementia. However, the relationship between microplastics and dementia is not necessarily causal; because dementia can cause impairment to the blood-brain barrier (thus impacting the brain’s ability to keep unwelcome particles out) a higher concentration of microplastics would be expected in the brain anyway, according to the study.

In lab studies, throwing microplastics on animal immune and gut cells alters them. It causes oxidative stress, which is a cellular imbalance that can lead to inflammation, says Eliseo Castillo, PhD, an associate professor and director of gastroenterology research at the University of New Mexico and a coauthor of the Nature Medicine study. So far, scientists like Castillo haven’t been able to fully determine what this inflammatory effect means for humans.

An interesting clue: a 2022 study in Environmental Science & Technology found that stools from participants with inflammatory bowel disease contained a higher concentration of microplastics than those without the disease. But again, that’s not to say that this association is causal. While Castillo hasn’t seen evidence of microplastics causing inflammation in a healthy human gut, he says it’s possible that microplastics could very well exacerbate inflammatory bowel disease.

While microplastics have not yet been found in human fetuses, scientists have found them in human placentas. Aagaard, who studies the connections between microplastics and reproductive health, coauthored a 2024 study in Toxicological Sciences that looked at 62 placenta samples and detected microplastics in all of them. In her more recent research, she also discovered that microplastic levels were elevated in placentae from preterm births compared to the placentae of full-term births.

While many studies have been done on animals, understanding cause and effect in humans is a bit harder. Mixing microplastics with animal cells in a petri dish is not the same as a human ingesting microscopic amounts of plastic over time, so it may not be an accurate enough way to look at microplastics in our system, says Castillo. The same limitation goes for feeding a lab mouse microplastics for weeks on end and studying the impact on the animal—that isn’t how humans ingest microplastics, so those studies may not be super accurate.

Plus, it’s difficult to keep microplastics out of samples in lab studies, says Castillo. Collection tubes, research instruments, and even air particles can contain microplastics, which can contaminate specimens in the lab. That doesn’t mean that plastics aren’t in the specimens; it just means that it’s hard to be completely certain of microplastic levels when the laboratory is full of microplastic contamination.

While researchers figure out the impact of microplastics on our bodies, here are some tips from the experts for minimizing exposure:

Until there’s more research on the long-term effects of microplastics on our bodies, you can follow those tips to decrease your exposure—and to reduce your overall plastic pollution while you’re at it. After all, using less plastic is better for you, your community, and the planet anyway; it’s a win-win.